The present invention relates to syndiotactic vinylaromatic polymer compositions containing impact modifiers. More particularly the present invention relates to such compositions wherein the impact modifier comprises an oil extended elastomeric polyolefin. The compositions may further be modified to incorporate crystal modifiers, compatibilizers, fillers, and optionally reinforcing aids. Surprisingly, according to the present invention, high temperature resistant syndiotactic vinylaromatic polymer compositions can be produced having improved elongation, rigidity and toughness.